The skin plays a very important role as a barrier protecting the body from the external environment. This barrier function is a protective function of defending the body from various external stimuli (e.g., chemicals, pollutants, dry environments, UV rays, etc.) and protecting the excessive loss of water from the body through the skin. This protective function can be maintained only when the horny layer consisting of keratinocytes is normally formed.
The Stratum corneum (horny layer) which is the outermost layer of the epidermis is formed of keratinocytes and consists of differentiated keratinocytes and lipid layers surrounding them (Marcelo C. L. et al, J. Invest. Dermatol., 80, pp. 37-44, 1983).
Keratinocytes are characteristic cells formed as basal cells that continuously proliferate in the lowest layer of the epidermis move up toward the skin's surface while they undergo stepwise changes in their morphology and function. After a given period of time, old keratinocytes are removed from the skin and replaced with new keratinocytes, and such a series of repeated changes is called “differentiation of epidermal cells” or “keratinization”.
In the keratinization process, keratinocytes form the horny layer while producing natural moisturizing factor (NMFs) and intracellular lipids (ceramide, cholesterol, fatty acid, etc.), such that the horny layer has firmness and flexibility so as to function as a skin barrier.
This horny layer can readily lose its function due to habitual factors such as excessive face washing or bathing, environmental factors such as dry pollutants, and endogenous diseases such as atopic skin or senile skin. In fact, due to various factors which are further increasing these days, people suffering from dry skin and various symptoms caused thereby are gradually increasing.
Accordingly, various studies have been conducted in order to supply water from the outside or prevent the loss of water from the body so as to maintain the skin water content at a suitable level. In fact, various moisturizers having water holding ability have been developed. As skin moisturizers, lipid components such as ceramide, and substances such as essential fatty acids and lipid complexes which can increase water holding in the horny layer are generally used (Rawlings A. V. et al, J. Invest. Dermatol., 5, pp. 731-741, 1994).
However, the risky factors for the skin gradually increase, the production and removal rates of the horny layer become slow due to the change of eating habits, the amount of moisturizing factors and lipids in the horny layer is decreased due to deterioration in the function of keratinocytes, and for these reasons, people having skins, the horny layer of which does not exhibit a normal skin barrier function, gradually increase. This breakdown of the skin barrier function will cause various skin diseases including dry skin, atopic dermatitis, contact dermatitis and psoriasis. Such diseases can be alleviated only by existing conventional moisturizers having water-holding function, but the fundamental treatment thereof with the conventional moisturizers is difficult.
As used herein, the term “Granate bark” refers to the cortex of the fruit, stem, branch and root of Punica granatum L. The plant Punica granatum L. has a yellow or yellowish red color when ripened. Also, the plant is a fleshy plant, and the outer bark often irregularly breaks to show seeds. In Chinese herbal medicine, the plant is used as a drug for stopping diarrhea, inhibiting intestinal bleeding, treating oral mucositis and tonsillitis, controlling insects, and preventing miscarriage and conception.
Seed of Prunus armeniaca refers to a dried seed obtained by removing a fruit flesh and a seed coat from the ripe fruit of an apricot tree belonging to the family Rosaceae. In Chinese herbal medicine, it is known to be effective in treating cough and asthma. Particularly, it has been reported to contain a large amount of unsaturated fatty acids, and thus have an excellent effect of relieving and softening the skin and also an excellent skin whitening effect.
Coix lacryma-jobi is the seed of Job's tears belonging to the family Gramineae. In Chinese herbal medicine, it is used to treat diarrhea, dropsy, headache and muscle cramp. The effective components thereof include coixol and sitosterol.
Saururus chinensis is a perennial dicotyledonous plant belonging to the family Saururaceae of the order Piperales, and the root and stem thereof have a white color and spread sideways in mud. The leaves thereof cross each other and have a pointed tip and a heart-shaped bottom. The surface of the leaves has a green color, and the back surface has a light white color, but 2-3 leaves present at the upper portion of the stem have a white surface. In Chinese herbal medicine, the whole plant is dried and used to treat body swelling and abnormal urination and also to treat beriberi, jaundice and hepatitis.
Perilla frutescens var. acuta refers to the leaf of a beefsteak plant which is an annual plant belonging to the family Labiatae. The stem of the plant has a square shape, stands up straight and has a height of 20-80 cm. The leaf of the plant has a broad oval shape similar to that of Perilla japonica, but has a purple color and strong fragrance and includes a sawtooth edge. In Chinese herbal medicine, the whole plant including roots is known to be effective in treating anemia, inhibiting perspiration, alleviating fever, treating bronchitis, cough and asthma, loosening phlegm, treating gastroenteritis, promoting digestion, treating vertigo, alleviating body pain, alleviating nasal obstruction, and reducing nasal discharge, and is used as an agent for treating poisoning by fishes.